Numerical Predictionon the Influence of Mixer on the Performance of Urea-SCR System

Authors: Kyoungwoo Park, Chol-Ho Hong, Sedoo Oh, Seongjoon Moon

Abstract:

Diesel vehicle should be equipped with emission after-treatment devices as NOx reduction catalyst and particulate filtersin order to meet more stringer diesel emission standard. Urea-SCR is being developed as the most efficient method of reducing NOx emissions in the after-treatment devices of diesel engines, and recent studies have begun to mount the Urea-SCR device for diesel passenger cars and light duty vehicles. In the present study, the effects of the mixer on the efficiency of urea-SCR System (i.e., NH₃uni- formityindex (NH₃ UI) is investigated by predicting the transport phenomena in the urea-SCR system. The three dimensional Eulerian-Lagrangian CFD simulationfor internal flow and spray characteristics in front of SCR is carried out by using STAR-CCM+ 7.06 code. In addition, the paper proposes a method to minimize the wall-wetting around the urea injector in order to prevent injector blocks caused by solid urea loading.

Keywords: Computational fluid dynamics, Multi-phase flow, NH3 uniformity index, Urea-SCR system, Urea-water-solution.

Digital Object Identifier (DOI): doi.org/10.5281/zenodo.1092848

References:

[1] M. Koebel, M. Elsener, T. Marti, NOx-reduction in diesel exhaust gas with urea and selective catalytic reduction, Combust. Sci. Tech. 121 (1996) 85-102.
[2] D.S. Yim, S.J.Kim, J.H.Baik, I, Nam, Y.S.Mok, J.W.Lee, B.K.Cho, S.H.Oh, Decomposition of Urea into NH3 for the SCR Process, Ind. Eng. Chem. Res. 43 (1) (2004) 4856-4863.
[3] M. Koebel, M. Elsener, and M. Kleemann, 2000, Urea-SCR: a Promising Technique to Reduce NOx emissions from automotive diesel engines, Catalysis Today, 59 (2000) 335-345.
[4] S.J. Jeong, S.J.Lee, W.S. Kim, C.B. Lee, Numerical study on the inhector shape and location of urea-SCR system of heavy duty diesel engine for preventing NH3 slip, Trans of KSAE, 14(1) (2006) 68-78.
[5] F. Birkhold, U. Meingast, P. Wassermann, O. Deutschmann, Modeling and simulation of a injection of urea-water-solution for automotive SCR DeNOx-system, Applied Catalysis B : Environmental, 70 (2007) 119-127.
[6] H. Strom, A. Lundstrom, B. Andersson, Choice of urea-spray models in CFD simulation of urea-SCR system, Chemical Engineering Journal 190 (2009) 69-82.
[7] F.R. Menter, Two-equation eddy-viscosity turbulence models for engineering applications, AIAA-Journal, 32(8) (1994) 269-289.
[8] D.P. Schmidt, Idr. Nouar, P.K. Senecal, C.J. Rutland, J.K. Martin, R.D. Reitz, Pressure-swirl atomization in the near field, SAE Technical Paper 1999-01-0496, (1999).
[9] R.D. Reitz and R. Diwaker, Effect of drop breakup on fuel sprays, SAE Technical Paper Series 860469.
[10] CATIA v5 Solutions. Version 5, Release 9, English Online Documentation, Generative Shape Design.
[11] STAR CCM+, User’s guide, Release 7.06(2013), CD-Adapco.